Features of Gas Exchange Surfaces (Cambridge (CIE) IGCSE Biology)
Revision Note
Written by: Lára Marie McIvor
Reviewed by: Lucy Kirkham
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Features of Gas Exchange Surfaces
The surfaces where gas exchange occurs in an organism are very different and different organisms have evolved different mechanisms for getting the gases to the gas exchange surface depending on size, where they live etc.
All gas exchange surfaces have features in common
These features allow the maximum amount of gases to be exchanged across the surface in the smallest amount of time
They include:
Large surface area to allow faster diffusion of gases across the surface
Thin walls to ensure diffusion distances remain short
Good ventilation with air so that diffusion gradients can be maintained
Good blood supply to maintain a high concentration gradient so diffusion occurs faster
The alveolus is the gas exchange surface in humans
Examiner Tips and Tricks
You may notice that several of the features of alveoli that make them suited to their function are the same as those that make villi suited to their function; or root hair cells suited to their function – the reason for this is because all of these structures are involved in transporting substances across their surfaces – by diffusion, active transport, osmosis or a combination.So if you learn the features for one, you also know many of the features of the others!
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